This happened to me on a non crossfire situation. There are 5 connectors on my saturn's engine harness. One of those connectors was having an intermittent connection. Because the problem code was somewhat unique I thought I would have a "professional" track down the problem. Two trips to the service department, Three weeks waiting and $1100 later the problem got solved. When dealerships have $120 hourly rates and they are really just experimenting; things can get out of hand. I'm happy for you that you had a competent mechanic working on the car.